1. Field of the Invention
This invention relates to an audio system installed inside a vehicle.
Recently, many audio systems installed inside vehicles have been provided with a plurality of speakers generally reproducing stereo sounds and fader controlling circuits for adjusting a volume of sound reproduced by the speakers, arranged on the left and right sides and in the front and rear seat areas.
More particularly, this invention relates to the improvement in the use of incorporating a sound field controller in the audio system through the fader controlling circuit The sound field controller being capable of reproducing sound quality equivalent to that of an actual concert hall.
2. Description of the Related Art
Generally, the fader controlling circuit adjusts sound volume reproduced by the speakers arranged in the front seat and the rear seat areas in the vehicle or on the left and the right sides therein to allow listeners of each seat to enjoy the feeling experienced from listening to a localized or rear sound source. On the other hand, the sound field controller consists of a sound system of a DSP (Digital Signal Processor) as shown in JAPANESE UNEXAMINED PATENT PUBLICATION (Kokai) No. 1-220599 and No. 1-220600, for example, which realizes the presence and feeling of sound distribution equivalent to an actual concert hall by artificially producing direct sound arriving or origination from the sound source of the music source signal to create sound fields. These sound fields are selected for the kinds of listened music and the user's preference, the sound field of the concert hall is, for example, suitable for the performance of a symphony orchestra, etc.
A vehicle installed apparatus for reproducing sound fields has formerly controlled reproduced signal levels of sound emitted from each speaker so that it adjusts the position of localization for aiming a direction of a sound source since the number and position of the listeners changes Thus, the apparatus adjusts the fader controlling circuits with balance volumes for the left and right sides and with fader volumes for the front and rear areas depending on the number and sitting position of persons in the vehicle.
On the other the sound field controller consisting of or including a DSP is designed and controlled on the assumption that each channel signal from the sound signal source is input thereto relative to signal levels as it is, for example, on the assumption that the left and right side signals or the front and rear area signals are input in a state such that the signal levels are not adjusted. Consequently, the sound field controller is constituted to obtain a maximum effect in the center position of the balance volume and the fader volume. Thus, in the prior or above apparatus for reproducing sound fields the balance volume and fader volume need to be manually adjusted to the center position if the maximum effect is to be realized.
Therefore, in the above prior art, if the listeners select the sound field control process, they must adjust the balance volume and fader volume. Also, in the case of relieving the sound field control process, the repeated adjustment of the balance volume and fader volume is required and the manipulation for the adjustment of the sound to the position of localization is complex, i.e., to have the signal level of the sound reproduced to a desired level. Particularly, the above same complexity of the manipulation occurs in the use of the sound field controller when adjustments to the audio system are required in order to change the reproduced signal levels of the front and rear area speakers, and left and right side speakers corresponding to a different environment. The vehicle installed system having been preset with the fader control circuit.